1. Field of the Invention
Systems used currently to inject sterile fluid medications into patients via the ports of intravenous (IV) access assemblies pose hazards to patients and to health care workers. For patients, the principal hazard is blood stream infections with skin- or glove-borne microorganisms caused by contamination of exposed needles, syringes, multiple dose vial caps or recesses in infusion ports suitable for bacterial colonization. For healthcare workers, the principal hazards are accidental needlesticks from exposed sharp hollow-bore steel needles while handling the equipment essential to the IV injection of sterile fluid medications into patients. By eliminating multiple dose vials, syringes, exposed needles, needleless systems and minimizing chances for contamination of caps through which sterile fluid medications are injected, the connectors are designed to reduce these mutual hazards.
2. Description of the Prior Art
For forty years medication filled cartridges, called carpules, with leading diaphragms and trailing pistons insertable into stainless steel aspirating syringes have been used by dentists for injecting anesthetics prior to performing painful procedures. The needles used are sharp on each end and housed in an externally threaded hub. The leading end of the needle is exposed for giving the injection. The trailing end of the needle which penetrates the diaphragm in the leading end of the carpule is stabilized by the threaded hub which is affixable to the leading end of a carpule aspirating syringe. The carpule piston is activated by a finger activated plunger permanently affixed inside the trailing end of the carpule aspirating syringe having trailing external flanges for finger placement and breech- or side-loading means for insertion of the carpule. The leading end of the plunger is supplied with a harpoon which temporarily engages the carpule piston such that the user can aspirate fluid from a patient into the carpule, as well as discharge the fluid contents of the carpule into a patient via the exposed leading end of the needle. Such carpules are traditionally made of glass for containing sterile liquid contents. However, they are not supplied with caps to keep the leading diaphragms sterile, or supplied individually in sterile packages which keep the entire external surfaces sterile. Formerly, dentists were advised to sterilize the external surfaces of the diaphragms on the leading ends of carpules with local antiseptics before insertion into carpule aspirating syringes, but now such antisepsis is seldom practiced.
Eliminating use of stainless steel carpule aspirating syringes, some dentists use disposable injectors, such as the Monoject.RTM. 418 disposable carpule aspirating injector. These consist of a plastic tube with a needle sharp on each end molded into the leading end of the injector, a bore for insertion of the carpule, and a trailing reusable plunger housed in a snap-on assembly with a permanently contained plunger having a harpoon on the leading end, a body through which the plunger slides with thumb ring activation and external flanges for finger placement. The trailing end of the sharp needle is safely recessed in the injector for penetrating the diaphragm on the leading end of the carpule. The exposed leading end of the sharp needle is supplied with a slip-on scabbard which is removed and not replaced after the carpule is inserted and the snap-on assembly is attached. After use, the assembly which snaps onto flanges on the trailing end of the injector is removed for reuse, and the injector containing the carpule is disposed as a unit with the leading end of the sharp needle exposed.
Some dentists use a modification of the Monoject.RTM. 418 system exemplified in the Ultrasafe.TM. Aspirating Syringe. This system differs in that the disposable carpule injector is supplied with a permanently attached outer sleeve which slides over a tubular plastic carpule holder and locks to cover the exposed leading end of the sharp needle after use in a patient; and in that the plunger assembly is not detached from the injector after use.
In medical practice, cartridges with initially scabbard-protected leading permanently attached sharp needles, bores filled with sterile liquid medications and trailing pistons releasably attachable to inserted plungers have been used for more than fifty years. The Wyeth Tubex.RTM. is an example. These generally employ a threaded bolt embodied in the trailing end of the cartridge piston which mates with a threaded receptacle in the leading end of a plunger and finger holding assembly, sometimes called a syrette. The leading needle is embodied in the cartridge, instead of attached to or attachable to a syringe assembly into which the cartridge is inserted via a hinging breech which locks shut in the long axis of the injecting holder/cartridge assembly, and opens to eject the spent cartridge/needle after use in a patient.
For user safety, the Tubex.RTM. systems have been modified recently by using a blunt cannula instead of a sharp needle on the leading end of the cartridge, as in some systems sold by Wyeth for accessing slit caps on intravenous access ports; or by using a clamp-on reusable plunger and finger holding assembly which releasably attaches to the trailing end of the cartridge with a sharp needle or a blunt cannula on the leading end.
A computer search for an injector or connector containing a recessed needle sharp on each end for discharging the sterile medicinal contents of a cartridge or a carpule into an intravenous infusion port found none. In U.S. Pat. No. 5,120,324 (Jun. 9, 1992), Sancoff disclosed a protected IV injection site coupling having a trailing means for connection to IV tubing and a leading housing containing a recessed needle for accessing an IV infusion port having a penetrable elastomeric cap. The leading end of the needle housing was slit and supplied with internal flanges for grasping the trailing end of the elastomeric cap. In U.S. Pat. No. 5,281,206 (Jan. 25, 1994), Lopez described a connector with a recessed needle with a rotatable collar for locking attachment of an attachable filled syringe to a branch port of an intravenous fluid flow line, such that the leading end of the injector can be stabilized over the injection port. In U.S. Pat. No. 5,735,823 (Apr. 7, 1998), Berger described a safety syringe having a sliding sleeve which allows filling of a syringe from a vial and then, with forward displacement of the sleeve over the syringe, allows locking of the syringe to an intravenous access system by a receptacle in leading end of the sliding sleeve to the main stream carrying limb of a Y-port, such that the leading bevel and shank of the syringe attached needle are not exposed during or after injection of the syringe contents. Search for a bias on the leading end of the injector for cradling the elastomeric cap on a standard Y-port on an IV infusion assembly, along with a needle sharp on each end found none.
Needles sharp on each end are commonly used in Vacutainer.TM. systems wherein the trailing end of the needle is temporarily or permanently recessed in a Vacutainer tube holder. However, the leading end of the needle, even though initially covered with a disposable scabbard, must be exposed to access the vein of a patient.
The instant patent application differs primarily from patents for medical cartridges and dental carpules in common use in that the recessed injector needle sharp on each end does not entail the use of a standard syringe or other means for reversibly attaching a syringe plunger to a piston for aspirating fluid, as well as for injecting fluid medication into a patient. Because the system disclosed herein injects into an infusion port of an established IV access system, instead of directly into a patient, there is no need to aspirate lymph or blood-tinged fluid from the patient to be sure of accurate placement of the needle. If the system were designed to aspirate fluid from the main stream in an IV access system, aspiration might dilute the fluid in the cartridge and, thus, potentially interfere with accurate volumetric measurement of fluid medication actually injected.
Traditionally, the Y-ports and simple ports on IV infusion assemblies have been serviced by using a sharp hollow needle to fill an attached syringe from a single or multiple dose vial and, then, using the same needle-attached syringe to penetrate and inject sterile liquid medication through the penetrable cap on the infusion port into the stream line of the IV access assembly. However since 1992, fear of accidental needlesticks with sharp needles whose bores potentially contain human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis B virus (HBV) spurred the development and use of needleless systems wherein blunt cannulae or syringe nozzles are used, instead of needles, to access modified infusion ports in IV infusion assemblies. A result has been a three to ten-fold increase in nosocomial blood stream infections in patients with skin- or glove-borne borne bacteria, when compared with the systems used traditionally. This increase appears partly owing to insufficient handwashing and use of unsterile gloves when handling the paraphernalia involved; and partly owing to recesses in the modified ports conducive to bacterial colonization with repeated use of blunt instruments passing through the same path of entry into the stream line.
The use of a shielded injector with or without a leading bias for cradling the elastomeric cap of a standard Y-infusion port was claimed in a patent, "Automatic Needle Shields for Safer Injections", currently pending for an elastomeric needle shielding system wherein the thrust of the needle beyond the leading end of the shield permits filling of a needle-attached syringe from a vial before injection into an IV access port. The instant disclosure differs in that a needle sharp on each end is permanently housed in a tubular injector, such that neither end of the needle is ever exposed to finger-touching during filling or use in a patient.
Fundamentally, the instant disclosure differs from the prior art in the following additional aspects:
1. The hollow bore needle sharp on each end is recessed such that neither end can be touched by a naked or a gloved finger. PA0 2. The cartridge or carpule can be supplied only partially filled, such that the trailing bore of the cartridge behind the piston supplies space for snug and stable insertion of a separate simple plunger which not only activates the cartridge piston in a leading direction, but also can be used to measure dosage injected. PA0 3. The leading end of the connector can be cut on a bias, such that leading end of the injector will not only cradle the elastomeric cap on a standard infusion port, but also gain stability by partly encircling the main stream limb of a Y-infusion port. PA0 4. The hollow needle in the injector can be eccentric, instead of concentric, in the long axis of the injector/cartridge assembly such that, by planned rotation of the injector in the long axis, passage of the needle through the same track in the elastomeric cap of an IV access cap can be avoided. PA0 5. The diaphragm on the leading end of the partly filled cartridge or carpule can be supplied with an easily removed hermetically sealing cap to keep the external surface sterile, in the event that the cartridge is not supplied in a separate sterile package. Preferably. the trailing end of the cap can be biased to assure easy removal before use of the cartridge.